Photomask and pattern forming method employing the same

ABSTRACT

A semitransparent phase shifting mask has, in the periphery of a pattern element area, a light shielding portion which is formed by a semitransparent phase shifting portion and a transparent portion with the optimal size combination. A pattern is formed employing the semitransparent phase shifting mask.

This is a continuation application of U.S. Ser. No. 08/904,754 now U.S.Pat. No. 5,851,703, filed Aug. 1, 1997, which is a continuationapplication of U.S. Ser. No. 08/699,732, filed Aug. 20, 1996, now U.S.Pat. No. 5,656,400, which is a continuation application of U.S. Ser. No.08/418,402, filed Apr. 7, 1995, now U.S. Pat. No. 5,578,421, which is adivisional application of U.S. Ser. No. 08/162,319, filed Dec. 7, 1993,now U.S. Pat. No. 5,429,896.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a photomask which is used tomanufacture a semiconductor device and the like, and more particularlyto a photomask which has been subjected to a processing of shifting aphase of exposure light beams and a pattern forming method employing thesame.

Along with an increase of the integration scale for semiconductordevices, sizes of patterns for forming constituent elements of thedevices become fine, and sizes equal to or smaller than the criticalresolution of a projection aligner are required. As a method offulfilling such a request, in JP-B-62-50811 published on Oct. 27, 1987,and corresponding to JP-A-57-62052 (laid open on Apr. 14, 1982) forexample, a photomask is employed in which a transparent film forshifting a phase of exposure light beams is provided on a transparentportion on one of the opposite sides sandwiching an opaque portion, andthus the resolution of a pattern is exceptionally improved.

In the above-mentioned prior art, a phase shifter needs to be arrangedin one of the transparent portions adjacent to each other, and for thearrangement of the phase shifter in the complicated element pattern,high trial and error is necessarily required. Thus, there is requiredconsiderable labor. In addition, since the number of processes ofmanufacturing a photomask is doubled as compared with the prior art, thereduction in yield and the increase in cost become problems.

Those problems can be settled by employing a semitransparent phaseshifting mask in which a semitransparent portion and a transparentportion are provided, and some of the light beams passed through thesemitransparent portion are phase-inverted with respect to light beamshaving passed through the transparent portion. With respect to thispoint, the description will hereinbelow be given with reference to theaccompanying drawings.

FIG. 1A is a cross sectional view showing a structure of an example of asemitransparent phase shifting mask. In the figure, reference numeral 1designates a transparent substrate, and reference numeral 2 designates asemitransparent film. A thickness of the semitransparent film 2 isadjusted such that the light beams having passed through the transparentportion 3 are phase-inverted with respect to the light beams havingpassed through a semitransparent portion 4. The semitransparent film 2has a transmittance such that a light beam having passed through thetransparent substrate 1 and the semitransparent film 2 has an intensityhigh enough to cause interference with a light beam having passedthrough the transparent substrate 1. The transparent film used in thisspecification means a film having the above-mentioned transmittance.

The light intensity distribution of the projected light beams on a waferbecomes, as shown in FIG. 1B, a sharp light intensity distribution. Thereason such a sharp light intensity distribution is obtained is that,since the light beams having passed through the transparent portion arephase-inverted with respect to the light beams having passed through thesemitransparent portion, the former and the latter cancel each other ina boundary portion of the pattern so that the light intensity becomesapproximately zero. In addition, since the intensity of the light beamshaving passed through the semitransparent portion is adjusted to beequal to or lower than the sensitivity of a photoresist, the intensityof the light beams having passed through the semitransparent portion isnot an obstacle to the formation of the pattern. That is, in thismethod, since the phase inversion effect between the pattern to betransferred and the semitransparent portion therearound is utilized,there is no need to take, as in the normal phase shifting mask, thearrangement of the phase shifter into consideration. In addition, in theprior art phase shift mask, the two lithography processes are requiredfor the formation of the mask. However, in this method, one lithographyprocess has only to be performed. Thus, it is possible to form the maskvery simply.

In this method, the light beams, which have an intensity that is equalto or lower than the sensitivity of a photoresist to which the patternof the mask is to be transferred, are made to pass through thesemitransparent film so that the light beams which have passed throughthe semitransparent film are phase-inverted with respect to the lightbeams which have passed through the transparent portion, and thus, thecontrast of the pattern is improved. As a result, it is possible toimprove the resolution of an aligner for transferring the mask pattern.The basic principle of the semitransparent phase shifting mask isdescribed in D. C. Flanders et al.: "Spatial Period Division--A NewTechnique for Exposing Submicrometer-Linewidth Periodic andQuasi-periodic Patterns" J. Vac. Sci. Technol., 16(6), Nov./Dec. pp 1949to 1952 (1979), U.S. Pat. Nos. 4,360,586 and 4,890,309 and JP-A-4-136854(laid open on May 11, 1992).

In the lithography process in which the above-mentioned semitransparentphase shifting mask is employed, in the normal exposed area, goodpattern formation can be performed. However, it has been made clear bythe investigations made by the present inventors that since in theactual exposure of the wafer, the mask pattern is repeatedly transferredby step-and-repeat exposure, the light beams which have leaked from thesemitransparent area, which is located outside the periphery of theactual pattern element corresponding to an active region of a substrate,leak out to the adjacent exposed area, and thus this is an obstacle togood pattern formation.

It is therefore an object of the present invention to provide aphotomask by which a good pattern can be obtained even in the case of anexposure, in which a mask pattern is repeatedly transferred bystep-and-repeat exposure, and a pattern forming method employing thesame.

According to one aspect of the present invention, the above-mentionedobject can be attained by effectively making a light-shielding or opaquearea of a semitransparent phase shift mask which is located outside theperiphery of a pattern element formation area of the semitransparentphase shifting mask.

The light shielding portion in the semitransparent phase shifting maskis formed by processing a semitransparent film to obtain a patternhaving a width equal to or lower than the resolution. The reason foradopting such a method is that if a light shielding film is newly formedas the light shielding portion, this will result in an increase of thenumber of processes of forming the mask. Incidentally, by optimizing thearea ratio of the semitransparent portion to the transparent portion, itis possible to further effectively form the light shielding portion.

These and other objects and many of the attendant advantages of theinvention will be readily appreciated as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are respectively a cross-sectional view showing astructure of a semitransparent phase shifting mask, and a view showingthe light intensity distribution of projected light beams on a waferwhen using the mask shown in FIG. 1A.

FIGS. 2A and 2B are respectively a plan view and a cross sectional vieweach showing a structure of a photomask according to the presentinvention.

FIG. 3A is a plan view showing a structure of a light shielding portionof the photomask according to the present invention.

FIG. 3B is a graphical representation showing the relationship betweenthe size of a transparent pattern of the photomask according to thepresent invention and the intensity of projected exposure light beams.

FIG. 4 is a plan view showing a structure of a mask for forming contactholes of a 64 MbitDRAM according to the present invention.

FIGS. 5A and 5B are respectively a plan view showing a structure of awindow pattern portion for aligning the position of the mask accordingto the present invention, and a view showing the light intensitydistribution of the projected light beams on the wafer when using themask shown in FIG. 5A.

FIGS. 6A through 6D are cross sectional views showing steps of a processof manufacturing a semi-conductor device according to the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

When both a semitransparent phase shifting pattern and a transparentpattern are arranged with the same size and at a pitch equal to or lowerthan the critical resolution, a pattern image can be erased. But, inthis case, the resulting uniform light intensity does not become zerobecause, since there is a difference between the quantity of light beamshaving passed through the semitransparent phase shifting portion andthat of light beams having passed through the transparent portion, thefunction of those light beams canceling each other due to the phaseinversion effect is not efficiently performed.

Then, when the ratio of the area of the semitransparent phase shiftingportion to that of the transparent portion is adjusted in accordancewith a set transmittance of the semitransparent phase shifting portion,it is made clear that the light intensity can be zero. By using thispattern for an area of a to-be-exposed wafer surface, which may beotherwise undesirably double-exposed by the step and repeat process byan aligner, it is possible to prevent the double exposure on the wafer,and a pattern of constituent elements as desired can be formed.Therefore, since the present photomask is made up of onlysemitransparent phase shifting portions and transparent portions, thereis no need to newly form a light shielding film for the formation of thelight shielding portion, and thus, the process of forming the photomaskcan be simplified.

Incidentally, the above-mentioned light shielding portion is applicableto the formation of a light shielding portion in a pattern elementregion of a substrate. In this case, since the ratio of thetransmittance of the transparent portion to that of the light shieldingportion can be made large, it is possible to increase the tolerance forthe variation of the quantity of light beams required for the exposure.

As for the materials used for the formation of the semitransparent phaseshifting portion, a lamination film of a semitransparent metal film(made of chromium, titanium or the like) or a silicide film (e.g., amolybdenum silicide film) and a silicon oxide film for the phase shift,or a single layer film such as a metal oxide film (e.g., a chromiumoxide film) or metal nitride film (e.g., a chromium nitride film) may beemployed. In the case where a single layer film such as a chromium oxidefilm or a chromium nitride film is employed, since the refractive indexthereof is larger than that of the silicon oxide film, the film can bethinned. As a result, since the influence of the light diffraction canbe reduced, this single layer film is suitable for the formation of afine pattern.

Embodiment 1

A first embodiment of the present invention will hereinafter bedescribed in detail. FIGS. 2A and 2B are respectively a plan view and across sectional view each showing the appearance of a photomask employedin the present embodiment. In those figures, reference numeral 1designates a transparent substrate, and reference numeral 5 designatesan element pattern portion in which both a semitransparent phaseshifting portion and a transparent portion are arranged. Moreover,reference numeral 6 designates a portion acting, on a wafer, as a lightshielding portion in which semitransparent phase shifting patterns arearranged at a pitch equal to or smaller than the resolution.

Reference numeral 7 designates a masking blade for shielding, on thealigner side, the exposure light beams. Since the masking blade 7 ispoor in positional accuracy, it is positioned so as to shield the lightbeams passing through the portion which is located outside theintermediate position of the width of the area 6 acting as the lightshielding portion.

The details of the area 6 acting as the light shielding portion willhereinbelow be described with reference to FIGS. 3A and 3B. FIG. 3A is aplan view showing a structure of a pattern. In this connection, eachtransparent pattern portion 10 is formed within a semitransparent phaseshifting portion 9. An arrangement pitch 11 of the transparent patterns10 is determined depending on the resolution characteristics of theprojection optical system employed. The arrangement pitch P is expressedby the following expression:

    P=α·λ/NA,

where NA represents a numerical aperture of a projection lens, λrepresents a wavelength of the exposure light beams, and a represents acoefficient.

In this connection, on the basis of the experiments made by the presentinventors, it is desirable that the coefficient α is set to a valueequal to or smaller than 0.8. However, the optimal value of α is notlimited thereto or thereby because the optimal value of α depends on thecharacteristics of the illuminating system, the pattern configurationand the like.

The width 12 of the transparent pattern 10 influences largely theformation of a dark portion. FIG. 3B shows the intensity of theprojected light beams which is obtained on the wafer when changing thewidth 12 of the transparent pattern 10. The, intensity of the projectedlight beams shows the intensity of the light beams which have passedthrough the pattern of FIG. 3A. The pitch of the transparent patterns 10was determined to be 0.4 μm by using α=0.1 in the expression of thearrangement pitch.

With respect to the three kinds of transmittance 9%, 16% and 25% of thesemitransparent phase shifting portion, the change in the intensity ofthe projected light beams were examined by changing the size of thetransparent pattern 10. The axis of abscissa of the graph represents thesize of the transparent pattern 10. From the graph of FIG. 3B, it can beseen that a minimum value is present in the intensity of the projectedlight beams depending on the size of the transparent pattern, and thislocal minimum value is variable depending on the transmittance of thesemitransparent phase shifting portion. That is, it can be seen that inaccordance with the transmittance of the semitransparent phase shiftingportion 9, an optimal transparent pattern size can be found.

Denoting the size ratio of size 12 of the transparent pattern to thesize 13 of the semitransparent phase shifting portion 13 by α, anoptimal value thereof will be expressed by the following expression:

    α=β·√T,

where T represents a transmittance of the semitransparent phase shiftingportion, and β represents a coefficient. The allowable intensity of theprojected light beams is variable depending on the intended purpose. Inthe case of preventing exposure of a photoresist due to a doubleexposure, the allowable intensity of the projected light beams may beset to about one-half the intensity of light which has passed throughthe semitransparent phase shifting portion. However, in the case ofpreventing a double exposure of a dark portion with a finepattern-containing portion, the change in the size of the fine patternneeds to be reduced as much as possible, and thus it is desirable thatthe allowable intensity of the projected light beams is set to a valueequal to or lower than 0.05. The value of β in this case is in the rangeof about 0.5 to about 2.0.

Then, the area 6 of FIG. 2A was formed on the basis of the optimalconditions thus obtained, and by actually using the projection aligner,the pattern element 5 corresponding to the active region was exposed bythe step and repeat process. As a result, a good pattern elementcorresponding to the active region could be formed without patterndestruction and size shifting even in the area in which the area 6 wasdoubled-exposed.

As described above, the semitransparent phase shifting portion and thetransparent portion were formed with the optimal size combination,whereby the effective dark portion could be formed. Incidentally,although in the present embodiment, the example is shown in which theline transparent pattern is formed in the semitransparent phase shiftingarea, the present invention is not limited thereto or thereby. That is,for example, there is particularly no problem even in the case of anisland-like pattern and other patterns. In such cases, if α in theexpression α=β·√T is replaced with the area ratio of the area of thetransparent pattern to the area of the semitransparent phase shiftingportion, substantially the same effects can be obtained.

In addition, in the present embodiment, the combination of thesemitransparent phase shifting pattern and the transparent pattern isapplied to prevent the double exposure. However, this application of thepresent invention is not limited thereto or thereby. It is, of course,to be understood that the combination is applicable to the necessaryportions such as a window pattern for aligning the mask position, apattern for detecting the wafer position, and a semitransparent phaseshifting portion having a large area, all of which require a lightshielding portion. Further, the above-mentioned photomask having a lightshielding portion is useful for pattern formation when manufacturing asemiconductor device.

Embodiment 2

A second embodiment of the present invention will hereinafter bedescribed with reference to FIG. 4.

FIG. 4 is. a plan view showing a structure of a photomask which is usedto form contact holes of a 64 Mbit dynamic random access memory (DRAM).Two DRAM element areas 5 are arranged in a transparent substrate 1. Ascribing area 14 is provided between the two pattern element areas 5. Inaddition, in a peripheral scribing area 15 on two sides perpendicular toeach other, a pattern for measuring the accuracy of the mask alignment,a target pattern for the mask alignment, and the like are arranged,which becomes necessary for the process of manufacturing a device.

In the two sides opposite to the other sides of the scribing area, apattern configuration 6' of light shielding portion 6 of the presentinvention is arranged. The step-and-repeat process in the projectionaligner is performed at a pitch 16 in the transverse direction and at apitch 17 in the longitudinal direction. The peripheral portion which islocated outside a dotted line 18 as the setting center is mechanicallyshielded from the light beams by a mechanical light shielding plate ofthe aligner. In this connection, the dotted line 18 is set at a distanceequal to or longer than the positional accuracy of the mechanical lightshielding plate from the scribing area such that the mechanical lightshielding plate is not shifted to the scribing area by mistake. Inaddition, the width of the pattern configiration 6' portion is set to avalue equal to or larger than the positional accuracy of the mechanicallight shielding plate, and the dotted line 18 is arranged in about thecentral portion of the pattern configuration 6'. Further, at least threeof the four corner portions have pattern configurations.

As a result of using this photomask in order to manufacture the 64MbitDRAM, double exposure in the periphery of the chip can be perfectlyprevented, and thus a good device can be manufactured. In addition, inthe case where the pattern element area 5 is formed by one chip, or thephotomask having the patter configuration 6' is applied to devices otherthan DRAM, the same effects can be obtained.

Further, a description will hereinbelow be given with respect to anexample in which the pattern configuration 6' of the present inventionis arranged in the periphery of a window pattern which is used to alignthe mask position with reference to FIGS. 5A and 5B. FIG. 5A is a planview showing a structure of the window pattern portion which is used toalign the mask position. FIG. 5B shows the distribution of the lightintensity on the wafer corresponding to the mask position.

As shown in FIG. 5A, a transparent portion 10 which has a sizefulfilling the conditions for forming the dark portion of FIG. 3B isformed around a window pattern 19. It can be seen that in thedistribution of the light intensity on the wafer of the photomask ofFIG. 5A at that time, the light intensity in the periphery of the windowpattern is, as shown in FIG. 5B, zero, and thus signals representing thewindow pattern are obtained with a high signal-to-noise (S/N) ratio andthe judgment of the position is performed with accuracy. In such a way,the light shielding pattern configuration of the present invention isapplicable to a pattern utilizing light intensity signals each having ahigh S/N ratio from a mask pattern and other patterns requiring thelight shielding portion as well as to the light shielding in theperiphery of a device chip.

Embodiment 3

Hereinbelow, an example will be shown in which a semiconductor device ismanufactured according to the present invention. FIGS. 6A through 6D arecross sectional views showing steps of a process of manufacturing asemiconductor device. By using the conventional method, a P type welllayer 21, a P type layer 22, a field oxide film 23, a polycrystallineSi/SiO₂ gate 24, a high impurity concentration P type diffusion layer25, a high impurity concentration N type diffusion layer 26, and thelike are formed in an N⁻ type Si substrate 20.

Next, by using the conventional method, an insulating film 27 made ofphosphor silicate glass (PSG) is deposited thereon. Then, a photoresist28 is applied thereto, and a hole pattern 29 is formed by using thesemitransparent phase shifting mask of the present invention (refer toFIG. 6B).

Next, an insulating film 27 is selectively etched by dry etching withthe resultant photoresist as an etching mask, thereby to form contactholes 30 (refer to FIG. 6C). Then, by using the conventional method, aW/TiN electrode wiring 31 is formed, and an interlayer insulating film32 is also formed.

Next, a photoresist is applied thereto, and then by using a conventionalmethod, a hole pattern 33 is formed using the semitransparent phaseshifting mask of the present invention. Then, a W plug is plugged in thehole pattern 33 to connect a second level Al wiring 34 there-to (referto FIG. 6D). In a subsequent passivation process, the conventionalmethod is employed.

Incidentally, in the present embodiment, only the main manufacturingprocesses have been described. In this connection, the same processes asthose of the conventional method are employed except that thesemitransparent phase shifting mask of the present invention is used inthe lithography process of forming the contact hole. By theabove-mentioned processes, CMOS LSI chips can be manufactured at a highyield.

As set forth hereinabove, according to the present invention, by formingthe semitransparent phase shifting portion and the transparent portionwith the optimal size combination, even if a light-shielding film is notnewly formed, the effective dark portion can be formed. In addition,without increasing the number of processes of forming the mask, apractical semitransparent phase shifting mask can be produced. Further,as a result of manufacturing the semiconductor device by using thephotomask of the present invention, it is possible to form a pattern inwhich the effects inherent in the semitransparent phase shifting maskare sufficiently utilized, without any problem in the double exposureportion, and also it is possible to realize the reduction of the devicearea.

It is further understood by those skilled in the art that the foregoingdescription is a preferred embodiment of the disclosed device and thatvarious changes and modifications may be made in the invention withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A pattern forming method comprising the stepsof:preparing a semitransparent phase shifting mask including (a) asemitransparent phase shifting pattern formed at a predeterminedposition on a photomask substrate and (b) a light shielding areaprovided at a peripheral edge portion of said semitransparent phaseshifting pattern and serving to make an intensity of light having passedthrough said light shielding area smaller than an intensity of lighthaving passed through said semitransparent phase shifting film, asmeasured on a to-be-exposed film; and exposing, with a projectionexposure optical system, said to-be-exposed film by use of saidsemitransparent phase shifting mask.
 2. A pattern forming methodcomprising the steps of:preparing a semitransparent phase shifting maskincluding (a) a first semitransparent phase shifting pattern having asemitransparent phase shifting film, said phase shifting film beingformed at a predetermined position on a photomask substrate and having atransmittance with respect to exposure light not higher than 25% and (b)a light shielding area provided at a peripheral edge portion of saidfirst semitransparent phase shifting pattern and serving to make anintensity of light having passed through said light shielding areasmaller than an intensity of light having passed through saidsemitransparent phase shifting film, as measured an a to-be-exposedfilm; preparing a substrate having a to-be-exposed film; and exposing,with a projection exposure optical system, said to-be-exposed film tosaid exposure light by use of said semitransparent phase shifting mask.3. A method according to claim 2, wherein said light shielding areaincludes a second semitransparent phase shifting pattern having asemitransparent phase shifting portion and a transparent portion.
 4. Amethod according to claim 3, wherein a ratio α of an area of saidtransparent portion to an area of said semitransparent phase shiftingportion is defined as α=β√T, where T represents a transmittance of saidsemitransparent phase shifting portion, and β represents a value in arange 0.5≦β≦2.0.
 5. A method according to claim 2, wherein a lightshielding portion is provided within a region for said firstsemitransparent phase shifting pattern, said light shielding portionserving to make an intensity of light having passed through said lightshielding portion smaller than an intensity of light having passedthrough said semitransparent phase shifting film, as measured on ato-be-exposed target.
 6. A method according to claim 2, wherein atransparent pattern is provided within said light shielding area to betransferred onto said to-be-exposed film.
 7. A method according to claim2, wherein said first semitransparent phase shifting pattern is apattern for forming a device.
 8. A pattern forming method comprising thesteps of:mounting a substrate having a photoresist film, on a samplestage of an aligner having a masking blade; mounting, on a mask supportof said aligner, a semitransparent phase shifting mask including (a) asemitransparent phase shifting pattern formed at a predeterminedposition on a photomask substrate and (b) a light shielding areaprovided at a peripheral edge portion of said semitransparent phaseshifting pattern and serving to make an intensity of light having passedthrough said light shielding area smaller than an intensity of lighthaving passed through said semitransparent phase shifting film, asmeasured on said photoresist film; and exposing said photoresist film byuse of said semitransparent phase shifting mask.
 9. A pattern formingmethod comprising the steps of:mounting a substrate having ato-be-exposed film, on a sample stage of an aligner having a maskingblade; mounting, on a mask support of said aligner, a semitransparentphase shifting mask including (a) a first semitransparent phase shiftingpattern having a semitransparent phase shifting film, said phaseshifting film being formed at a predetermined position on a photomasksubstrate and having a transmittance with respect to exposure light nothigher than 25% and (b) a light shielding area provided at a peripheraledge portion of said first semitransparent phase shifting pattern andserving to make an intensity of light having passed through said lightshielding area smaller than an intensity of light having passed throughsaid semitransparent phase shifting film, as measured on a to-be-exposedfilm; exposing a first area of said to-be-exposed film by use of saidSemitransparent phase shifting mask; moving said sample stage in ahorizontal direction; and exposing a second area, different from saidfirst area, of said to-be-exposed film by use of said semitransparentphase shifting mask.
 10. A method according to claim 9, wherein saidlight shielding area includes a second semitransparent phase shiftingpattern having a semitransparent phase shifting portion and atransparent portion.
 11. A method according to claim 10, wherein a ratioα of an area of said transparent portion to an area of semitransparentphase shifting portion is defined as α=β√T, where T represents atransmittance of said semitransparent phase shifting portion, and βrepresents a value in a range 0.5≦β≦2.0.
 12. A method according to claim9, wherein a light shielding portion is provided within a region forsaid first semitransparent phase shifting pattern, said light shieldingportion serving to make an intensity of light having passed through saidlight shielding portion smaller than an intensity of light having passedthrough said semitransparent phase shifting film, as measured on ato-be-exposed film.
 13. A method according to claim 9, wherein atransparent pattern is provided within said light shielding area to betransferred onto said to-be-exposed film.
 14. A method according toclaim 9, wherein said first semitransparent phase shifting pattern is apattern for forming a device.
 15. A method according to claim 9, whereinsaid second area includes a portion of said to-be-exposed film which isshielded by said light shielding area in said step of exposing saidfirst area of said to-be-exposed film.
 16. A method of manufacturing asemiconductor device, comprising the steps of:preparing asemitransparent phase shifting mask including (a) a firstsemitransparent phase shifting pattern for formation of a semiconductordevice having a semitransparent phase shifting film, said phase shiftingfilm being formed at a predetermined position on a photomask substrateand having a transmittance with respect to exposure light not higherthan 25% and (b) a light shielding area provided at a peripheral edgeportion of said first semitransparent phase shifting pattern and servingto make an intensity of light having passed through said light shieldingarea smaller than an intensity of light having passed through saidsemitransparent phase shifting film, as measured on a to-be-exposedfilm; preparing a substrate having a to-be-exposed film; and exposing,with a projection exposure optical system, said to-be-exposed film tosaid exposure light by use of said semitransparent phase shifting mask.17. A method according to claim 16, wherein said light shielding areaincludes a second semitransparent phase shifting pattern having asemitransparent phase shifting portion and a transparent portion.
 18. Amethod according to claim 17, wherein a ratio α of an area of saidtransparent portion to an area of semitransparent phase shifting portionis defined as α=β√T, where T represents a transmittance of saidsemitransparent phase shifting portion, and β represents a value in arange 0.5≦β≦2.0.
 19. A method according to claim 16, wherein a lightshielding portion is provided within a region for said firstsemitransparent phase shifting pattern, said light shielding portionserving to make an intensity of light having passed through said lightshielding portion smaller than an intensity of light having passedthrough said semitransparent phase shifting film, as measured on ato-be-exposed target.
 20. A method according to claim 16, wherein atransparent pattern is provided within said light shielding area to betransferred onto said to-be-exposed film.
 21. A method of manufacturinga semiconductor device, comprising the steps of:mounting a substratehaving a to-be-exposed film, on a sample stage of an aligner having amasking blade; mounting, on a mask support of said aligner, asemitransparent phase shifting mask including (a) a firstsemitransparent phase shifting pattern for formation of a semiconductordevice having a semitransparent phase shifting film, said phase shiftingfilm being formed at a predetermined position on a photomask substrateand having a transmittance with respect to exposure light not higherthan 25% and (b) a light shielding area provided at a peripheral edgeportion of said first semitransparent phase shifting pattern and servingto make an intensity of light having passed through said light shieldingarea smaller than an intensity of light having passed through saidsemitransparent phase shifting film, as measured on a to-be-exposedfilm; exposing a first area of said to-be-exposed film by use of saidsemitransparent phase shifting mask; moving said sample stage in ahorizontal direction; and exposing a second area, different from saidfirst area, of said to-be-exposed film by use of said semitransparentphase shifting mask.
 22. A method according to claim 21, wherein saidlight shielding area includes a second semitransparent phase shiftingpattern having a semitransparent phase shifting portion and atransparent portion.
 23. A method according to claim 22, wherein a ratioα of an area of said transparent portion to an area of saidsemitransparent phase shifting portion is defined as α=β√T, where Trepresents a transmittance of said semitransparent phase shiftingportion, and β represents a value in a range 0.5≦β≦2.0.
 24. A methodaccording to claim 22, wherein a light shielding portion is providedwithin a region for said first semitransparent phase shifting pattern,said light shielding portion serving to make an intensity of lighthaving passed through said light shielding portion smaller than anintensity of light having passed through said semitransparent phaseshifting film, as measured on a to-be-exposed target.
 25. A methodaccording to claim 22, wherein a transparent pattern is provided withinsaid light shielding area to be transferred onto said to-be-exposedfilm.
 26. A method of manufacturing a semiconductor device, comprisingthe steps of:forming an impurity-doped layer in a predetermined regionof a semiconductor substrate; forming an insulating film on saidsemiconductor substrate having said doped layer formed therein; forminga photoresist film on said insulating film; mounting said substratehaving said photoresist film, on a sample stage of an aligner having amasking blade; mounting, on a mask support of said aligner, asemitransparent phase shifting mask including (a) a firstsemitransparent phase shifting pattern for formation of a hole having asemitransparent phase shifting film, said phase shifting film beingformed at a predetermined position on a photomask substrate and having atransmittance with respect to exposure light not higher than 25% and (b)a light shielding area provided at a peripheral edge portion of saidfirst semitransparent phase shifting pattern and serving to make anintensity of light having passed through said light shielding areasmaller than an intensity of light having passed through saidsemitransparent phase shifting film, as measured on said photoresistfilm; and exposing a first area of said photoresist film by use of saidsemitransparent phase shifting mask; moving said sample stage in ahorizontal direction; exposing a second area, different from said firstarea, of said photoresist film by use of said semitransparent phaseshifting mask; and, thereafter etching said insulating film to form ahole above said impurity doped layer.
 27. A method of manufacturing asemiconductor device, comprising the steps offorming a wiring layerabove a predetermined region of a semiconductor substrate; forming aninsulating film on said semiconductor substrate having said wiring layerformed thereabove; forming a photoresist film on said insulating film;mounting said substrate having said photoresist film, on a sample stageof an aligner having a masking blade; mounting, on a mask support ofsaid aligner, a semitransparent phase shifting mask including (a) afirst semitransparent phase shifting pattern for formation of a holehaving a semitransparent phase shifting film, said phase shifting filmbeing formed at a predetermined position on a photomask substrate andhaving a transmittance with respect to exposure light not higher than25% and (b) a light shielding area provided at a peripheral edge portionof said first semitransparent phase shifting pattern and serving to makean intensity of light having passed through said light shielding areasmaller than an intensity of light having passed through saidsemitransparent phase shifting film, as measured on said photoresistfilm; and exposing a first area of said photoresist film by use of saidsemitransparent phase shifting mask; moving said sample stage in ahorizontal direction; exposing a second area, different from said firstarea, of said photoresist film by use of said semitransparent phaseshifting mask; and, thereafter etching said insulating film to form ahole above said wiring layer.
 28. A method of manufacturing asemiconductor device, comprising the steps of:preparing asemitransparent phase shifting mask including (a) a firstsemitransparent phase shifting pattern for formation of a semiconductordevice having a semitransparent phase shifting film, said phase shiftingfilm being formed at a predetermined position on a photomask substrateand having a transmittance with respect to exposure light not higherthan 25% and (b) a light shielding area provided at a peripheral edgeportion of said first semitransparent phase shifting pattern; preparinga substrate having a to-be-exposed film, said light shielding area ofsaid semitransparent phase shifting mask serving to make an intensity oflight having passed through said light shielding area not larger than0.05, as measured on said to-be-exposed film; and exposing, with aprojection exposure optical system, said to-be-exposed film to saidexposure light by use of said semitransparent phase shifting mask.
 29. Amethod according to claim 28, wherein said light shielding area includesa second semitransparent phase shifting pattern having a semitransparentphase shifting portion and a transparent portion.
 30. A method accordingto claim 29, wherein a ratio α of an area of said transparent portion toan area of said semitransparent phase shifting portion is defined asα=β√T, where T represents a transmittance of said semitransparent phaseshifting portion, and β represents a value in a range 0.5≦β≦2.0.
 31. Amethod according to claim 28, wherein a light shielding portion isprovided with a region for said first semitransparent phase shiftingpattern, said light shielding portion serving to make an intensity oflight having passed through said light shielding portion smaller than anintensity of light having passed through said semitransparent phaseshifting film, as measured on a to-be-exposed target.
 32. A methodaccording to claim 28, wherein a transparent pattern is provided withinsaid light shielding area to be transferred onto said to-be-exposedfilm.
 33. A method of manufacturing a semiconductor device, comprisingthe steps of:mounting a substrate having a to-be-exposed film, on asample stage of an aligner having a masking blade; mounting, on a masksupport of said aligner, a semitransparent phase shifting mask including(a) a first semitransparent phase shifting pattern for formation of asemiconductor device having a semitransparent phase shifting film, saidphase shifting film being formed at a predetermined position on aphotomask substrate and having a transmittance with respect to exposurelight not higher than 25% and (b) a light shielding area provided at aperipheral edge portion of said first semitransparent phase shiftingpattern and serving to make an intensity of light having passed throughsaid light shielding area not larger than 0.05, as measured on saidto-be-exposed film; exposing a first area of said to-be-exposed film byuse of said semitransparent phase shifting mask; moving said samplestage in a horizontal direction; exposing a second area, different fromsaid first area, of said to-be-exposed film by use of saidsemitransparent phase shifting mask.
 34. A method according to claim 33,wherein said light shielding area includes a second semitransparentphase shifting pattern having a semitransparent phase shifting portionand a transparent portion.
 35. A method according to claim 34, wherein aratio α of an area of said transparent portion to an area of saidsemitransparent phase shifting portion is defined as α=β√T, where Trepresents a transmittance of said semitransparent phase shiftingportion, and β represents a value in a range 0.5≦β≦2.0.
 36. A methodaccording to claim 34, wherein a light shielding portion is providedwithin a region for said first semitransparent phase shifting pattern,said light shielding portion serving to make an intensity of lighthaving passed through said light shielding portion smaller than anintensity of light having passed through said semitransparent phaseshifting film, as measured on a to-be-exposed target.
 37. A methodaccording to claim 34, wherein a transparent pattern is provided withinsaid light shielding area to be transferred onto said to-be-exposedfilm.